Fiber-reinforced alkali-activated composite (FRAC) was studied with the aim of recycling solid wastes and developing a sustainable high-performance building material. FRACs were prepared by the alkali-activation of binary waste ashes: Fly ash (FA) and ground granulated blast furnace slag (GGBS), and various contents of ceramic-based short basalt fibers (BFs) of 0.2%, 0.4%, 0.6% and 0.8% (volume/volume %). The engineering properties of compressive strength, tensile strength and flexural strength measurements obtained at different aging of 3, 7 and 28 days, were used to assess the mechanical characteristics of the composite against a control mortar mix containing 0% BF. The obtained results showed a significant improvement in the strength characteristics and toughness of the alkali-activated matrix due to incorporation of high modulus BFs. Maximum tensile and flexural strengths were obtained with the highest BF content of 0.8%, while, the maximum compressive strength was achieved at the optimum fiber content of 0.6%, which achieved about 108% of the control mix strength. Moreover, conducted microstructure analysis explained the positive effect of BFs incorporation into the matrix. The high modulus fibers worked on relived the matrix by absorption some of the stresses through the interface between matrix and fiber and. Thus, improved the matrix toughness.
